Shape memory embolectomy devices and systems

ABSTRACT

An embolectomy device comprised of an expansion unit and a support unit is disclosed. The expansion unit can be actuated in response to one or more external stimuli, and the support unit, located proximately to the expansion unit, provides a force to hold the expansion unit in place and to further induce the expansion unit&#39;s radial expansion. The radial expansion of the expansion unit causes the expansion unit to physically contact a blood clot, enabling the blood clot to be removed. In some embodiments, the expansion unit can be fabricated from a shape memory polymer foam. In some embodiments the support unit can be fabricated from any elastic material including, without limitation, shape memory alloys.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/094,701, filed Apr. 8, 2016, which claims priority to U.S.Provisional Patent Application No. 62/144,432 filed on Apr. 8, 2015 andentitled “SHAPE MEMORY EMBOLECTOMY DEVICE.” The content of each of theabove applications is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This disclosure was made with Federal Government support under Grant No.R01EB000462 awarded by the National Institute of Biomedical Imaging andBioengineering. The Government has certain rights in the disclosure.Additionally, the United States Government has rights in thisapplication pursuant to Contract No. DE-AC52-07NA27344 between theUnited States Department of Energy and Lawrence Livermore NationalSecurity, LLC for the operation of Lawrence Livermore NationalLaboratory.

TECHNICAL FIELD

The present disclosure provides an embolectomy device comprised of shapememory materials, exhibiting shape memory and mechanical propertiesoptimized for removing blood clots from occluded blood vessels.

BACKGROUND

The presence of a blood clot blocking blood flow in the circulatorysystem causes thromboembolic vascular disease. Venous thromboembolismsaffect more than 900,000 Americans each year, with 30% of those dyingwithin 30 days and another 30% affected by recurring venousthromboembolisms within ten years.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present invention willbecome apparent from the appended claims, the following detaileddescription of one or more example embodiments, and the correspondingfigures. Where considered appropriate, reference labels have beenrepeated among the figures to indicate corresponding or analogouselements.

FIG. 1 depicts an example embolectomy device, configured to be insertedinto a blood vessel with an occlusive blood clot in accordance with anembodiment of this disclosure.

FIG. 2A depicts an example embolectomy device in a non-actuatedconfiguration in accordance with an embodiment of this disclosure.

FIG. 2B depicts an example embolectomy device in an actuatedconfiguration in accordance with an embodiment of this disclosure.

FIG. 3A depicts the deployment of an example embolectomy device within ablood vessel with an occlusive blood clot in accordance with anembodiment of this disclosure.

FIG. 3B depicts actuation of the example embolectomy device to remove anocclusive blood clot in accordance with an embodiment of thisdisclosure.

FIG. 3C depicts removal of a blood clot from a blood vessel using theexample embolectomy device in accordance with an embodiment of thisdisclosure.

FIG. 4A depicts an example of a support unit of an embolectomy device ina relaxed state in accordance with an embodiment of this disclosure.

FIG. 4B depicts an example of a support unit of an embolectomy device ina deformed state in accordance with an embodiment of this disclosure.

FIG. 5 is a flow diagram illustrating example operations to fabricate anembodiment of the disclosed embolectomy device in accordance with anembodiment of this disclosure.

FIG. 6 is a flow diagram illustrating example operations to use anembodiment of the disclosed embolectomy device to remove an occlusiveblood clot from a blood vessel in accordance with an embodiment of thisdisclosure.

FIG. 7 is an experimental example of a disclosed embolectomy device inaccordance with an embodiment of this disclosure.

FIG. 8 depicts experimental examples of the support unit of thedisclosed embolectomy device in accordance with an embodiment of thedisclosure.

FIGS. 9A, 9B, and 9C depict an example set-up to produce an embodimentof a support unit according to an embodiment of the disclosure.

FIG. 10 depicts an alternative embodiment of a support unit according toan embodiment of the disclosure.

FIGS. 11A and 11B depict an implementation of a support unit in arelaxed and deformed state, respectively, according to an embodiment ofthe disclosure.

FIG. 12 depicts an embodiment of the disclosed embolectomy devicedeployed in an experimental setup of a blood vessel according to anembodiment of the disclosure.

FIG. 13 depicts an embodiment of the disclosed embolectomy devicedeployed in an experimental setup equipped with a device capable ofmeasuring tensile forces according to an embodiment of the disclosure.

FIGS. 14A and 14B depict certain experimental results derived fromtensile testing of certain embodiments of the embolectomy deviceaccording to embodiments of the disclosure.

FIG. 15 depicts the maximum and average failure forces for differentexperimental embodiments of the embolectomy device according toembodiments of the disclosure.

DETAILED DESCRIPTION AND EXEMPLARY EMBODIMENTS

Reference will now be made to the drawings wherein like structures maybe provided with like suffix reference designations. In order to showthe structures of various embodiments more clearly, the drawingsincluded herein are diagrammatic representations of structures. Thus,the actual appearance of the fabricated structures, for example in aphotograph, may appear different while still incorporating the claimedstructures of the illustrated embodiments. Moreover, the drawings mayonly show the structures useful to understand the illustratedembodiments. Additional structures known in the art may not have beenincluded to maintain the clarity of the drawings. “An embodiment”,“various embodiments” and the like indicate embodiment(s) so describedmay include particular features, structures, or characteristics, but notevery embodiment necessarily includes the particular features,structures, or characteristics. Some embodiments may have some, all, ornone of the features described for other embodiments. “First”, “second”,“third” and the like describe a common object and indicate differentinstances of like objects are being referred to. Such adjectives do notimply objects so described must be in a given sequence, eithertemporally, spatially, in ranking, or in any other manner. “Connected”may indicate elements are in direct physical or electrical contact witheach other and “coupled” may indicate elements co-operate or interactwith each other, but they may or may not be in direct physical orelectrical contact.

Applicant has determined conventional stent-like embolectomy devicesfail to adequately mitigate distal embolization from blood clotfragmentation. Additionally, Applicant has determined the length ofstent-like embolectomy devices reduces the maneuverability of thesestent-like devices. These and other limitations necessitate a solution.

A disclosed embodiment is directed to an embolectomy device comprised ofshape memory (SM) components. In one embodiment, an embolectomy deviceis comprised of a guidewire, at least one expansion unit, and at leastone support unit. The expansion unit can be comprised of a shape memorypolymer (SMP) foam in some embodiments. The support unit can becomprised of an elastic material, such as SM alloys and SMPs in someimplementations. The support unit is configured to include struts thatcurve outward from the guidewire. The at least one support unit isaffixed to the guidewire, and the at least one expansion unit is affixedto the guidewire proximate to the at least one support unit. The supportunit provides structural support to the expansion unit. Additionally,the support unit can be fabricated in a geometry that collapses to asmall radius after being forced into a small volume, such as the lumenof a catheter. Due to its elastic properties, the support unit canrecover its larger radius geometry after entering a space with a largervolume. Actuation of the expansion unit causes the expansion unit toexpand substantially in volume. In an embodiment, the expansion unit canbe comprised of a SMP foam, which can be actuated through application tothe SMP foam of any of heat, a solvent, laser irradiation, or resistiveheating. Actuation refers to providing an external stimulus (e.g.,exposure to warm blood or bodily fluids) to the expansion unit thatinduces the expansion unit to expand in volume. The support unitcompresses against the expansion unit, holding the expansion unit inplace and causing the expansion unit to expand outward radially, fillingthe occluded blood vessel and preventing a blood clot from slippingaround the disclosed embolectomy device.

Another embodiment is directed to a method for removing blood clotsusing an embodiment of the embolectomy device. An embodiment of anembolectomy device can be advanced through a blood vessel and past ablood clot occluding the blood vessel. The expansion unit of theembolectomy device can be actuated to cause the volume of the expansionunit to increase substantially. Consequently, the expansion unit canphysically contact the blood clot. The expanded size of the expansionunit can preclude the blood clot or pieces of the blood clot fromescaping. The embolectomy device and catheter are retracted from thesite of the blood clot, causing the blood clot to be dragged in thedirection of the retraction. As the embolectomy device is dragged, theresulting force causes the support unit to press against the expansionunit, holding the expansion unit in place and inducing further radialexpansion of the expansion unit. In one embodiment, the embolectomydevice and catheter can be dragged to the location of a sheath,introduced into the blood vessel, and the sheath can be used to capturethe blood clot. The sheath, containing the blood clot, can be removed.

A further embodiment of the disclosure is directed to a method formaking an embodiment of the disclosed embolectomy device. A plurality ofslits is cut into a segment of an elastic material to form a supportunit containing struts. The support unit is heated. The support unit iscooled. The support unit is affixed to a guidewire. An expansion unit isexcised from a homogeneous mass of SMP foam. The expansion unit isaffixed to the guidewire proximate to the support unit.

As noted above, the description herein includes exemplary devices andmethods that embody the present disclosure. However, it is understoodthat the described embodiments may be practiced without these specificdetails. For example, although FIG. 1 depicts an embodiment of anembolectomy device that includes a single expansion unit and a singlesupport unit, other embodiments of the embolectomy device may include aplurality of expansion units and a plurality of support units.Additionally, although depictions of the support unit show a designatednumber of struts, fewer or more struts may be present in variousembodiments of the support unit of the disclosed embolectomy device.Moreover, in some implementations, the at least one expansion unit canbe epoxied onto the at least one support unit.

In an embodiment an embolectomy device can be comprised of a guidewire;at least one expansion unit; and at least one support unit, cut tocontain a plurality of slits configured to form a flower-like structurecomprised of a plurality of struts. The at least one support unit can beaffixed to the guidewire. The at least one expansion unit can be affixedto the guidewire. The at least one expansion unit can be situatedproximately to the support unit. The expansion unit can be comprised ofa SMP foam. The support unit can be comprised of an elastic materialsuch as a SM alloy or a SMP. Stainless steel and nitinol arenon-limiting examples of SM alloys from which the support unit can becomprised.

In an embodiment, the embolectomy device can be appended to a catheter.The catheter, configured with the embolectomy device, can be advancedinto a blood vessel containing a blood clot, and the embolectomy devicecan be advanced past a blood clot within the blood vessel. The expansionunit of the embolectomy device can be actuated to expand significantlyin volume. In one embodiment, the expansion unit of the embolectomydevice can be expanded by plasticization. For instance, water heated toapproximately 37 degrees centigrade can induce the expansion unit of theembolectomy device to expand outward radially, thereby enlargingsignificantly in diameter. The term actuation refers to causing anexpansion unit to transition from a crimped initial state to an expandedstate by providing a stimulus to the expansion unit.

Hence, due to this outward radial expansion, the expansion unit of theembolectomy device can physically contact the blood clot. The expansionunit can contact the blood clot in a direction perpendicular to bloodflow. The struts of the support unit of the embolectomy device cancontact the expansion unit, holding the expansion unit in place. Thus,the expansion unit can capture the blood clot, holding the blood clot inplace, and the support unit can hold the expansion unit in place,further compressing the expansion unit and further forcing it to expandoutward radially. The embolectomy device and catheter can be retractedfrom the site of the blood clot, causing the blood clot to be dragged.In one embodiment, a sheath can separately be introduced into the bloodvessel, and the blood clot can be dragged into the sheath. The sheath,with the blood clot located within it, can be removed. Due to the radialexpansion of the expansion unit, which can capture the blood clot, andthe deformation of the support unit, which can hold the expansion unitin place and which can induce further radial expansion of the expansionunit due to an axial force placed on the expansion unit, the embolectomydevice needs only be advanced on the order of a centimeter or lessoutside the catheter to capture a blood clot.

FIG. 1 illustrates an example embodiment of the embolectomy device 100.The embolectomy device 100 includes a guidewire 104, an expansion unit108, and a support unit 112. The support unit 112 can be affixed to theguidewire 104. The expansion unit 108 also can be affixed to theguidewire 104.

The expansion unit 108 may be comprised of any low density SMP foam insome embodiments. SMP foams exhibit an entropically driven SM effect.For example, the expansion unit 108 may be comprised from those SMPfoams generally described in United States Patent ApplicationPublication Number 20140142207 A1 entitled “Ultra Low DensityBiodegradable Shape Memory Polymer Foams with Tunable PhysicalProperties.” In one embodiment, an expansion unit can be crimped to 20%of its initial diameter and can retain its ability to recover itsinitial geometry, thereby providing a mechanism advance such anexpansion unit through a catheter. However, in other embodimentsdifferent low density SMP foams can be used to constitute the expansionunit 108. For example, a SMP foam described in United States PatentApplication Publication 20140142207A1 could be chemically modified tobind to blood clots. The SMP unit 108 can be fabricated from thechemically modified SMP foam. Although depicted as cylinder, theexpansion unit 108 can be fashioned into any geometry optimized tocapture a blood clot. For instance, the expansion unit 108 can befashioned into a sphere, a cone, or a barrel in some embodiments. SMPfoams can expand in volume by as much as seventy times their originalvolumes. In an embodiment, an expansion unit can be comprised of a SMPfoam with a low glass transition temperature Tg; hence, exposure toblood can cause these expansion units to actuate.

The support unit 112 may include a plurality of struts 116, 120, 124,and 128 that expand outward from the guidewire 104. The length of theplurality of struts 116, 120, 124, and 128 can vary, thereby affectingthe dimensions of the support unit 112. The support unit 112 can befabricated from any elastic material that exhibits a pseudoelasticeffect. For example, the support unit 112 can be fabricated from any ofnitinol, stainless steel, platinum, a platinum alloy, or other elasticmetal alloy. The support unit 112 also can be fabricated from a SMP. Inone embodiment, the support unit 112 can be fabricated from a segment ofnitinol tubing. Nitinol can recover from strains of up to eight percent.An excimer laser can be used to cut a plurality of slits lengthwise inthe nitinol tubing. These slits can form struts that fashion the nitinoltubing into a flower-like structure, wherein each strut constitutes a“petal” of the flower-like structure as depicted in FIG. 1. As theembolectomy device is moved through a blood vessel, the support unit 112can deform, pushing against the expansion unit 108, holding theexpansion unit 108 in place and causing the expansion unit 108 tofurther expand outward radially, thereby increasing the surface areacontact between the expansion unit 108 and a blood clot. Since thesupport unit 112 can be set through mechanical constraint and heattreatment, the support unit 112 can be fabricated in a geometry thatcollapses to a small radius after being forced into the lumen of acatheter or other delivery device. Pushing the support unit 112 outsidea catheter or other shape constrained delivery device can permit thesupport unit 112 to recover the larger radius geometry of the supportunit 112. The guidewire 104 can be fabricated from any of nitinol,stainless steel, or a platinum alloy. The guidewire 104 also can befabricated from other materials that can withstand high strains. In someembodiments, the guidewire 104 may be replaced with another suitablesubstrate capable of withstanding strain while providing a support forthe support unit 112 and the expansion unit 108.

FIG. 2A illustrates the disclosed embolectomy device 200 in a crimped,non-actuated state. FIG. 2B depicts the disclosed embolectomy device 200in an actuated state. In embodiments in which the expansion unit 108 ofthe embolectomy device 200 is fabricated from SMP foams, the expansionunit 108 can be actuated by exposure of the expansion unit 108 to waterat a temperature range of between 20 degrees centigrade and 100 degreescentigrade. Similarly, when deployed in the body, heat from blood can beused to induce actuation of the expansion unit 108 in some embodiments.In other implementations, any of a solvent, laser irradiation, orresistive heating can be employed to actuate the expansion unit 108 inembodiments in which the expansion unit 108 is formed from SMP foams.

FIGS. 3A, 3B, and 3C depict use of an embolectomy device 330A, 330B,330C to remove a blood clot 308A, 308B, 308C from a blood vessel 320A,320B, 320C. FIG. 3A illustrates a blood vessel 320A occluded with ablood clot 308A. In an embodiment, an embolectomy device 330A comprisedof a guidewire 324A, an expansion unit 312A, and a support unit 316A canbe affixed to a catheter 304A. As illustrated in FIG. 3A, theembolectomy device 330A is in a non-actuated state. The embolectomydevice 330A in a non-actuated state can be guided past the blood clot308A. The embolectomy device 330A can be actuated. In one embodiment,water heated to between 20 degrees centigrade and 100 degrees centigradecan be delivered through the catheter to contact the expansion unit312A, 312B, 312C. Heat from contact with the water can induce theexpansion unit 312A, 312B, 312C to actuate, thereby leading to asignificant expansion of the volume of the expansion unit 312A, 312B,312C as depicted in FIG. 3B in embodiments in which the expansion unit312A, 312B, 312C is fabricated from a SMP foam. As shown in FIG. 3B, theexpansion unit 312B is in physical contact with the blood clot 308B,immobilizing the blood clot. The support unit 316B provides support tothe expansion unit 312B, holding the expansion unit 312B in place.Additionally, the support unit 316B can exert an axial force on theexpansion unit 312B causing the expansion unit 312B to further expandoutward radially, thereby increasing the surface area contact betweenthe expansion unit 312B and the blood clot 308B. Therefore, theexpansion unit 312B holds the blood clot 308B in place, and the supportunit 316 holds the expansion unit 312B in place. As illustrated in FIG.3C, a force 334C can be applied to extract the blood clot 308C. As theembolectomy device 330C is pulled in the direction of the force 334C,the expansion unit 312C can push against the blood clot 308C. The force334C can cause the struts 338C of the support unit 316C to deform,thereby exerting a force against the expansion unit 312C.

FIGS. 4A and 4B depict the support unit 430A, 430B in a relaxed stateand a deformed state, respectively. In an embodiment, the support unit430A, 430B can be fashioned from nitinol. For example, an excimer lasercan be used to cut a plurality of slits into a segment of nitinoltubing. In one embodiment, four such slits can be created, but in otherembodiments fewer or more slits can be fashioned. The slits can beconfigured to form the struts 412A,412B, 416A, 416B, 420A, 420B, 424A,424B shown in FIGS. 4A and 4B, permitting the support unit 430A, 430B tobe configured in the geometry shown in FIGS. 4A and 4B. Hence, thenitinol tubing, containing the struts, can be placed into an aluminumfixture to compress the nitinol tubing into a flower-like geometry, asshown, for example, in FIGS. 4A and 4B. Larger diameter nitinol tubingcan form collars 404A, 408A, 404B, 408B to constrain and direct thecompression of the nitinol to a configuration that serves to reducestress on the more fragile sections of the support unit 430A, 430B. Inone embodiment, the support unit 430A, 430B can be affixed to a nitinolguidewire 434A, 434B by using a 1064 nm YAG laser welder. Othertechniques can be used to affix the support unit 430A, 430B to theguidewire 434A, 434B. As illustrated in FIG. 4B, the struts 412A, 412B,416A, 416B, 420A, 420B, and 424A, 424B can expand outward from theguidewire 434A, 434B.

FIG. 5 is a flow chart 500 that depicts example operations to fabricatethe disclosed embolectomy device. At 504 slits are cut into a segment ofan elastic material to form a support unit. At 508, the support unit canbe heated. For instance, a furnace can be used to heat the support unit.At 512, the support unit can be cooled. For example, room temperaturewater can be used to quench the support unit. At 516, the support unitcan be affixed onto a guidewire. In one embodiment, the support unit canbe welded onto the guidewire. For instance, a laser welder can be usedto affix the support unit onto the guidewire. At 520, an expansion unitcan be excised from a homogeneous mass of SMP foam. In one embodiment,the expansion unit can be in the form of a cylinder. In otherembodiments, the expansion unit can be fashioned into different shapes.For example, in an embodiment, a cylinder of SMP foam that isapproximately 1.5 times the diameter of a blood vessel to be treated canbe fashioned into an expansion unit. At 524, the expansion unit iscleaned and etched. For example, chemical washes can be used to cleanand etch the expansion unit. At 528, the expansion unit is affixed ontothe guidewire proximate to the support unit. In one embodiment, theexpansion unit can be crimped onto the guidewire using a stent crimper,thereby drastically reducing the diameter of the expansion unit. Theexpansion unit can be fabricated from SM foams described in Singhal, P.,Rodriguez, J. N., Small, W., Eagleston, S., Van de Water, J., Maitland,D. J., and Wilson, T. S., 2012, “Ultra low density and highlycrosslinked biocompatible shape memory polyurethane foams,” Journal ofPolymer Science Part B: Polymer Physics 50 (10), pp. 724-737.

FIG. 6 is a flow chart 600 that depicts example operations for use ofthe disclosed embolectomy device to remove a blood clot from an occludedblood vessel. At 604, the embolectomy device is placed on a catheter. At608, the disclosed embolectomy device is advanced through the catheterand past the blood clot. At 612, the expansion unit is actuated, causingit to increase substantially in volume. In one embodiment, water at atemperate between 20 degrees centigrade and 100 degrees centigrade canbe used to actuate the expansion unit in embodiments in which theexpansion unit is comprised of SMP foams. In other embodiments, solventscan be used to actuate the expansion unit in implementations in whichthe expansion unit is comprised of SMP foams. As the expansion unitexpands in volume, the expansion unit contacts the blood clot.Meanwhile, the support unit remains in contact with the expansion unit,pressing against the expansion unit and causing the expansion unit tofurther contract and expand outward radially. At 616, the disclosedembolectomy device and catheter is retracted from the site of the bloodclot. As the embolectomy device is directed away from the site of theblood clot, the embolectomy device drags the blood clot along. In anembodiment, a sheath can be inserted near the site of the blood clot,and the blood clot can be dragged into the sheath. At 620, the sheathand blood clot can be removed.

FIG. 7 depicts an example embodiment of the disclosed embolectomy device700. The support unit 704 was fabricated from nitinol. In particular, apiece of nitinol tubing was cut using an excimer laser cutter (RapidX,Resonetics). The shape of the cut nitinol tubing consisted of a 7 mmsection of 0.016″ OD and 0.013″ ID tubing cut with 4, 5 mm long axialslits with a 1 mm gap on each of the edges of the slits. The slits werespaced equally around the radius of the nitinol tubing. The cut nitinoltubing with slits was placed over a 0.010″ diameter nitinol wire androlled on 600 grit sandpaper for 30 seconds to remove burs created bylaser cutting. The cut nitinol tubing was etched using 5 M potassiumhydroxide (KOH) for 30 minutes at 120 o C. while being stirred with amagnetic stirring bar. The cut nitinol tubing also was placed in asonicator (3510, Branson) with a 100% isopropyl alcohol solution for oneminute to remove any soluble dirt particles from the surface of the cutnitinol tubing. FIG. 8 is an image of the cut nitinol tubing 800. Thecut nitinol tubing 800 is depicted before etching and sanding 804 andafter etching and sanding 808. The cut, sanded, and etched nitinoltubing 808 was placed into an aluminum fixture to compress the nitinoltubing into a flower-like geometry.

FIG. 9 depicts the aluminum fixture 900 used to form the support unit704. The aluminum fixture 900 was fabricated from a sliding aluminumwedge placed within a hollowed-out channel in an aluminum block 904. Ascrew 908 was placed into a threaded hole on one of the ends of thealuminum block 904 to provide force to move the block down the channel.Screws 912, 916 also were placed upright in the sliding portion 924 andthe aluminum block 904 in threaded holes. A hole was bored through theshank of each upright screw at the same height. To set the shape of thenitinol tubing, a wire was placed through the center of the nitinoltubing, which was subsequently placed through the holes on the twoupright screws in the aluminum fixture 900. Washers were secured aroundthe wire to hold it in place. By inserting the screw used to push thesliding component 924, the nitinol tubing was compressed between the twosets of washers on each screw, which served to constrain the nitinoltubing into a compressed secondary geometry 920. Heating in a furnace at550 degrees C., followed by quenching in room temperature water, set theunstrained shape to match the compressed secondary geometry 920.

In some embodiments of the procedure employed to fabricate the supportunit 704, the amount of axial compression was varied to affect thefailure force during tensile testing. In some embodiments, the supportunit 704 was compressed from an axial length of 7 mm to 6.25 mm, but inother implementations, the SM ally unit 704 was compressed from 7 mm to5.75 mm of axial length.

FIG. 10 illustrates an alternative implementation of a support unit1000. As depicted in FIG. 10, sections of larger diameter nitinoltubing, referred to as collars 1004, 1008, were used during the shapesetting process to constrain and direct the compression of the nitinolto a configuration that served to reduce stress on the more fragilesections of the support unit 1000. The collars 1004, 1008 placed aroundthe nitinol tubing were typically 1.5 mm in length and 0.023″ OD and0.020″ ID.

As shown in FIG. 11, an embodiment of the support unit 1104 was affixedto a guidewire 1108. In an implementation, the support unit 1104 wasaffixed to a 5′ segment of 0.010″ nitinol guidewire 1108 using a 1064 nmYAG laser welder (i990, LaserStar). In this embodiment, the support unit1104 was welded at the distal tip of the guidewire 1108 to allow forcompression 1112 of the support unit 1104 when a force 1116 was appliedto the proximal end of the support unit 1104.

To fabricate the expansion unit, a cylinder of SMP foam oversized toapproximately 1.5 times the diameter of the blood vessel to be treatedwas excised from a block of SMP foam. The targeted blood vessel to betreated was 4 mm in diameter; therefore, a 6 mm diameter sample of SMPfoam was used. A 6 mm biopsy punch was used to remove the SMP foamsample from a large block of SMP foam. A razor blade was used to cut thesample of SMP foam to an axial length of 5 mm. The SMP foam sample wasput into a stent crimper (SC250, Machine Solutions), where the diameterof the SMP foam sample was drastically reduced to a new crimped geometryafter being heated to 100 degrees C. The SMP foam sample was cooled toroom temperature over the course of two hours to set the secondarygeometry of the SMP foam sample. The SMP foam sample was transferredfrom the crimping wire to a nitinol guidewire. The crimped diameter ofthe resulting expansion unit was approximately 1 mm.

In one embodiment, the expansion unit was epoxied to the support unit.UV curable, medical grade epoxy was spread around a proximal collar of asupport unit using a cotton swab. The expansion unit was placed aroundthe epoxied portion and was secured to the support unit thoughattachment to the collar. The UV epoxy was cured using a UV light(Series 1000, OmniCure).

In an implementation, a pusher portion of nitinol tubing was placedproximal to the expansion unit. In such an embodiment, the pusher can beincluded to provide pushing force on the surface of the expansion unitto prevent it from sliding along the guidewire as the embolectomy deviceis advanced towards a blood clot. In this particular embodiment, thepusher was constructed by welding a 2.5 mm piece of 0.016″ OD and 0.013″ID nitinol tubing around the guidewire of the embolectomy device. Then alarger diameter, similar length piece of tubing made from 0.023″ OD and0.020″ ID nitinol was welded around the smaller piece of tubing toensure that the pusher could provide enough surface area to produceadequate force to move the expanding expansion unit along the catheter.The distal end of the pusher was located ˜13 mm from the tip of theguidewire to allow for the support unit to be compressed radially andexpanded axially when placed in a catheter without interfering with thepusher or expansion unit.

FIG. 12 depicts an experimental setup 1200 involving an embodiment ofthe disclosed embolectomy device 1220. The embodiment of the embolectomydevice 1220 included a support unit 1204 and an expansion unit 1208. Asdepicted in FIG. 12, the expansion unit 1208 has been actuated. In thedepicted implementation, the embolectomy device 1220 was delivered tothe site of a blood clot 1216 via a catheter 1224. In particular and aspart of the experiment, a 5F catheter 1224 was deployed through a Luerlock, and the tip of the catheter 1224 was placed distal to the bloodclot 1216. The catheter 1224 was flushed with body temperature water inan attempt to remove bubbles from the experimental setup 1200. Theembolectomy device 1220 was fed through the lumen of the catheter 1224and advanced out of the catheter 1224 to permit expansion of theexpansion unit 1208. In one implementation of the experimental setup1200, a syringe filled with body temperature water was injected throughthe catheter 1224 around an embodiment of the embolectomy device 1220 toinduce actuation of the expansion unit of the embolectomy device 1220.In the experimental setup 1200, once the embolectomy device 1220 wasdeployed, the catheter 1224 was retracted proximal to the blood clot1216, and the embolectomy device 1220 was used to extract the blood clot1216.

Retraction force studies were performed in connection with theexperimental setup 1200. The experimental setup 1200 was modified asdepicted in FIG. 13 to measure tensile forces to which an embodiment ofthe embolectomy device 1220 was subjected. The modified experimentalsetup 1300 includes a blood vessel model 1328, a catheter 1332, anembodiment of the embolectomy device 1316, a tensile tester 1304, aperistaltic pump 1308, a water bath 1312, and a discharge container1320. An embodiment of the embolectomy device 1316 was affixed to thetensile tester (MTS, Synergie, 50 N load cell as an example) 1304through a clamp around the proximal tip of the guidewire of anembodiment of the embolectomy device 1316. The remainder of theguidewire of an embodiment of the embolectomy device 1316 went through aconduit to align the embodiment of the embolectomy device 1316. The endof the alignment conduit acted as a stopper by providing a hole that wassufficiently large to pass the guidewire and support unit of theembodiment of the embolectomy device 1316 but too small to pass theexpansion unit of the embodiment of the embolectomy device 1316. Forcecaused by the tensile tester 1304 pulling on the guidewire compressedthe expansion unit and the support unit of the embodiment of theembolectomy device 1316 against the stopper until the embodiment of theembolectomy device 1316 failed. Failure was evidenced by a sharp dropoff in force being recorded by the tensile tester 1304. Retraction forcewas measured as the tensile tester 1304 pulled an embodiment of theembolectomy device 1316 and blood clot 1324 through the mock-up bloodvessel 1328 at a rate of 75 mm/minute.

Various experimental embodiments of the embolectomy device were testedusing the experimental setup described in FIG. 13. FIG. 14 illustratesexperimental results along with images of the support unit of eachtested implementation of the embolectomy device. In one experiment, anembodiment of the embolectomy device, the support unit 1404 of which isdepicted in FIG. 14, withstood forces of, on average, 7.43±0.94 N.

FIG. 15 tabulates maximum and average forces 1500 that four differentembodiments of the embolectomy device withstood. The solid lines in FIG.15 depict an average of five experimental trials conducted for each ofthe four experimental embodiments of the embolectomy device, and thepoints in FIG. 15 depict the maximum force that each such experimentalembodiment of the embolectomy device withstood. For instance, the line1504 illustrates the average of five trials that a first experimentalembodiment of the embolectomy device withstood, while the point 1508depicts the maximum force that a first experimental embodiment of theembolectomy device withstood.

The following examples pertain to further embodiments.

Example 1 includes an embolectomy device comprised of: a guidewire; atleast one expansion unit, configured to expand in diameter whenactuated; and at least one support unit, configured to exert a force onthe expansion unit; wherein: the at least one expansion unit is affixedto the guidewire, the at least one support unit is affixed to theguidewire, and the at least one expansion unit is situated proximatelyto the at least one support unit.

Example 2 includes the embolectomy device of example one, wherein the atleast one expansion unit is comprised of a SMP foam, the SMP foamcapable of expanding in diameter when actuated.

Example 3 includes the embolectomy device of example two, wherein the atleast one expansion unit comprised of the SMP foam can be actuated byany one of heat, exposure to a solvent, laser irradiation, and resistiveheating.

Example 4 includes the embolectomy device of example one, wherein the atleast one support unit is comprised of any one of a SM alloy; a SMP; andan elastic material, the elastic material capable of recovering fromdeformations.

Example 5 includes the embolectomy device of example four, wherein theat least one support unit comprised of the SM alloy is comprised of anyone of nitinol, stainless steel, and a platinum alloy.

Example 6 includes the embolectomy device of example four, wherein theat least one support unit comprised of the elastic material is comprisedof any of one of platinum and SMPs.

Example 7 includes the embolectomy device of example one, wherein theguidewire is comprised of any one of nitinol, stainless steel, platinum,platinum alloy, and any other material capable of withstanding strain.

Example 8 includes the embolectomy device of example one, wherein the atleast one support unit exerts an axial force on the at least oneexpansion unit, causing the at least one expansion unit to furtherexpand outward radially due to exertion of the axial force.

Example 9 includes the embolectomy device of example 8, wherein the atleast one support unit exerts an axial force on the at least oneexpansion unit after actuation of the at least one expansion unit.

Example 10 includes the embolectomy device of example one, wherein theat least one support unit includes a plurality of struts, the strutscapable of expanding radially outward from the guidewire.

Example 11 includes the embolectomy device of example ten, wherein theplurality of struts of the at least one support unit are fashioned to bestraight.

Example 12 includes the embolectomy device of example ten, wherein theplurality of struts of the at least one support unit are fashioned toform an ‘S’ shape.

Example 13 includes the embolectomy device of example one, wherein theat least one support unit is affixed to the guidewire through welding.

Example 14 includes the embolectomy device of example one, wherein theat least one expansion unit is affixed to the guidewire by crimping theexpansion unit onto the guidewire.

Example 15 includes the method for removing an embolus using theembolectomy device of example one, comprising: advancing the embolectomydevice of example one through a blood vessel and past an embolus withinthe blood vessel; actuating the at least one expansion unit of theembolectomy device of example one; retracting the embolectomy device ofexample one from a site of the embolus, causing the embolus to bedragged with the embolectomy device of example one.

Example 16 includes the method of example 15, wherein retracting theembolectomy device of example one from the site of the embolus furthercomprises: dragging the embolectomy device of example one and theembolus to a location of a sheath introduced within the blood vessel;capturing the embolus within the sheath; and removing the sheathcontaining the embolus.

Example 17 includes the method of example 15, wherein advancing theembolectomy device of example one through the blood vessel furthercomprises affixing the embolectomy device of example one onto a catheterand advancing the catheter together with the embolectomy device throughthe blood vessel and past the embolus.

Example 18 includes the method for fabricating the embolectomy device ofexample one comprising: cutting a plurality of slits into a segment ofan elastic material; constraining the elastic material containing theplurality of slits to a defined shape to form the at least one supportunit of the embolectomy device of example one; heating the support unit;cooling the support unit; affixing the support unit to a guidewire;cutting from a homogenous mass of SMP foam the at least one expansionunit of the embolectomy device of example one; and affixing theexpansion unit to the guidewire.

Example 19 includes the method of example 18, wherein constraining theelastic material containing the plurality of slits to a defined shape toform the support unit of the embolectomy device of example one furthercomprises constraining the elastic material containing the plurality ofslits to a shape designed to support the expansion unit.

Example 20 includes the method of example 19, wherein constraining theelastic material containing the plurality of slits to a shape designedto support the expansion unit further comprises constraining the elasticmaterial containing the plurality of slits to a shape capable ofexerting an axial force on the expansion unit.

Example 21 includes the method of example 18, wherein cutting aplurality of slits into a segment of an elastic material furthercomprises deburring the elastic material.

Example 22 includes the method for fabricating the embolectomy device ofexample one, the method comprising: forming a thermoplastic polymerelastic material into a specific shape designed to support the at leastone expansion unit of the embolectomy device of example one;crosslinking the thermoplastic polymer material to form the support unitof the embolectomy device of example one; affixing the support unit to aguidewire; compressing the support unit to a diameter less than theinner diameter of a delivery catheter; cutting from a homogenous mass ofSMP foam the at least one expansion unit of the embolectomy device ofexample one; and affixing the expansion unit to the guidewire.

Example 23 includes the method for fabricating the embolectomy device ofexample one, the method comprising: any one of machining a thermosetpolymeric elastic material and casting reactive monomers to a thermosetpolymer elastic material in a mold to form the support unit of theembolectomy device of example one; affixing the support unit to aguidewire; compressing the support unit to a diameter less than theinner diameter of a delivery catheter; cutting from a homogenous mass ofSMP foam the expansion unit of the thrombectomy device of example one;affixing the expansion unit to the guidewire.

Example 24 includes the method of examples 18 through 23, whereinfabricating the embolectomy device of example one further comprisescleaning the expansion unit.

Example 25 includes the embolectomy device comprised of: at least oneexpansion unit, configured to expand in diameter when actuated; at leastone support unit, configured to exert a force on the expansion unit;wherein: the at least expansion unit is situated proximally to the atleast one support unit, and each of the at least one expansion unit andthe at least one support unit is affixed to a substrate.

Example 26 includes the embolectomy device of example 25, wherein the atleast one expansion unit is comprised of a SMP foam capable of expandingin diameter when actuated.

Example 27 includes the embolectomy device of example 26, wherein the atleast one expansion unit comprised of the SMP foam is actuated throughany one of heat, exposure to a solvent, laser irradiation, and resistiveheating.

Example 28 includes the embolectomy device of example 25, wherein the atleast one support unit is comprised of any one of a SM alloy; a SMP; andan elastic material, the elastic material capable of recovering fromdeformations.

Example 29 includes the embolectomy device of example 28, wherein the atleast one support unit comprised of a SM alloy is comprised of any ofnitinol, stainless steel, and a platinum alloy.

Example 30 includes the embolectomy device of example 28, wherein the atleast one support unit comprised of an elastic material is comprised ofany one of platinum and SMPs.

Example 31 includes the embolectomy device of claim 25, wherein thesubstrate is a guidewire.

Example 32 includes the embolectomy device of example 31, wherein theguidewire is comprised of any one of nitinol, stainless steel, platinum,platinum alloy, and any other material capable of withstanding strain.

Example 33 includes the embolectomy device of example 25, wherein the atleast one support unit exerts an axial force on the at least oneexpansion unit, causing the at least one expansion unit to furtherexpand outward radially due to the exertion of the axial force.

Example 34 includes the embolectomy device of example 33, wherein the atleast one support unit exerts an axial force on the at least oneexpansion unit after actuation of the at least one expansion unit.

Example 35 includes the embolectomy device of example 25, wherein the atleast one support unit includes a plurality of struts, the strutscapable of expanding radially outward from the substrate.

Example 36 includes the embolectomy device of example 35, wherein theplurality of struts of the at least one support unit are fashioned to bestraight.

Example 37 includes the embolectomy device of example 35, wherein theplurality of struts of the at least one support unit are fashioned toform an ‘S’ shape.

Example 38 includes the embolectomy device of example 25, wherein the atleast one support unit is affixed to the substrate through welding.

Example 39 includes the embolectomy device of example 25, wherein the atleast one expansion unit is affixed to the substrate by crimping theexpansion unit onto the substrate.

Example 40 includes the method for removing an embolus using theembolectomy device of example 25, comprising: advancing the embolectomydevice of example 25 through a blood vessel and past an embolus withinthe blood vessel; actuating the at least one expansion unit of theembolectomy device of example 25; retracting the embolectomy device ofexample25 from a site of the embolus, causing the embolus to be draggedwith the embolectomy device of example 25.

Example 41 includes the method of example 40, wherein retracting theembolectomy device of example 25 from the site of the embolus furthercomprises: dragging the embolectomy device of example 25 and the embolusto a location of a sheath introduced within the blood vessel; capturingthe embolus within the sheath; and removing the sheath containing theembolus.

Example 42 includes the method of example 40, wherein advancing theembolectomy device of example 25 through the blood vessel furthercomprises affixing the embolectomy device of example 25 onto a catheterand advancing the catheter together with the embolectomy device throughthe blood vessel and past the embolus.

Example 43 includes the method for fabricating the embolectomy device ofexample 25 comprising: cutting a plurality of slits into a segment of anelastic material; constraining the elastic material containing theplurality of slits to a defined shape to form the at least one supportunit of the embolectomy device of example 25; heating the support unit;cooling the support unit; affixing the support unit to the substrate ofthe embolectomy device of example 25; cutting from a homogenous mass ofSMP foam the at least one expansion unit of the embolectomy device ofexample 25; and affixing the expansion unit to the substrate of theembolectomy device of example 25.

Example 44 includes the method of example 43, wherein constraining theelastic material containing the plurality of slits to a defined shape toform the support unit of the embolectomy device of example 25 furthercomprises constraining the elastic material containing the plurality ofslits to a shape designed to exert an axial force on the at least oneexpansion unit of the embolectomy device of example 25.

Example 45 includes the method of example 43, wherein cutting aplurality of slits into a segment of an elastic material furthercomprises deburring the elastic material.

Example 46 includes the method for fabricating the embolectomy device ofexample 25, the method comprising: forming a thermoplastic polymerelastic material into a specific shape designed to support the at leastone expansion unit of the embolectomy device of example 25; crosslinkingthe thermoplastic polymer material to form the support unit of theembolectomy device of example 25; affixing the support unit to asubstrate of the embolectomy device of example 25; compressing thesupport unit to a diameter less than the inner diameter of a deliverycatheter; cutting from a homogenous mass of SMP foam the at least oneexpansion unit of the embolectomy device of example 25; and affixing theexpansion unit to the substrate of the embolectomy device of example 25.

Example 1a includes an apparatus comprising: a pusher rod havingproximal and distal ends; a shape memory polymer (SMP) foam slidablycoupled to the pusher rod and adjacent the distal end of the pusher rod;and a shape memory (SM) metal coupled to the pusher rod distal to theSMP foam; wherein (a)(i) a distal portion of the SM metal is permanentlyaffixed to the pusher rod at a distal location and a proximal portion ofthe SM metal is slideably coupled to the pusher rod at a proximallocation that is proximal to the distal location; (a)(ii) in anon-expanded configuration the SM metal and the SMP foam each have firstmaximum diameters orthogonal to the pusher rod; and (a)(iii) in anexpanded configuration the SM metal and the SMP foam each have secondmaximum diameters orthogonal to the pusher rod and greater than therespective first maximum diameters.

Example 2a includes the apparatus of example la, wherein (b)(i) in thenon-expanded configuration the SM metal and the SMP foam each have firstmaximum lengths parallel to the pusher rod; (b)(ii) in the expandedconfiguration the SM metal and the SMP foam each have second maximumlengths parallel to the pusher rod; (b)(iii) the first maximum length ofthe SMP foam is shorter than the second maximum length of the SMP foamand the first maximum length of the SM metal is longer than the secondmaximum length of the SM metal.

Example 3a includes the apparatus of example 2a, wherein in the expandedconfiguration the proximal portion of the SM metal forces the SMP foam(c)(i) axially parallel to the pusher rod, and (c)(ii) radiallyorthogonal to the pusher rod and away from the pusher rod.

Example 4a includes the apparatus of example 2a, wherein (c)(i) thefirst maximum length of the SMP foam is shorter than the second maximumlength of the SMP foam by a SMP foam differential distance and the firstmaximum length of the SM metal is longer than the second maximum lengthof the SM metal by a SM metal differential distance; and (c)(ii) the SMPfoam differential distance is greater than the SM metal differentialdistance.

Example 5a includes the apparatus of example 2a, wherein SM metalcomprises at least two struts that couple the distal portion of the SMmetal to the proximal portion of the SM metal.

Example 6a includes the apparatus of example 5a comprising a conduitcoupled to proximal portions of the at least two struts, wherein theconduit is slideably coupled to the pusher rod.

Example 7a includes the apparatus of example 6a wherein the conduitslides distally along the pusher rod when the SM metal transitions fromthe non-expanded configuration to the expanded configuration.

Example 8a includes the apparatus of example 7a, wherein the conduit andthe at least two struts are all monolithic with each other.

Example 9a includes the apparatus of example 6a comprising an additionalconduit coupled to distal portions of the at least two struts.

Example 10a includes the apparatus of example 5a wherein the at leasttwo struts directly contact a distal face of the SMP foam in theexpanded configuration.

Example 11a includes the apparatus of example 10a wherein the at leasttwo struts are substantially linear in the non-expanded configurationand substantially arcuate in the expanded configuration.

Example 12a includes the apparatus of example 10a wherein the at leasttwo struts do not contact the distal face of the SMP foam in thenon-expanded configuration.

Example 13a includes the apparatus of example 2a wherein the pusher rodpasses through the SMP foam and at least a portion of the SM metal whenthe SMP foam and the SM metal are each in the non-expandedconfiguration.

Example 14a includes the apparatus of example 13a, wherein a firstportion of the pusher rod is proximal to the SMP foam, a second portionof the pusher rod passes through the SMP foam when the SMP foam is inthe non-expanded configuration, and a third portion of the pusher rodpasses through the portion of the SM metal when the SM metal is in thenon-expanded configuration.

Example 15a includes the apparatus of example 14a, wherein the first,second, and third portions of the pusher rod are monolithic with eachother.

Example 16a includes the apparatus of example 2a, wherein the SMP foamtransitions from the unexpanded configuration to the expandedconfiguration in response to thermal stimulus.

Example 17a includes the apparatus of example 2a, wherein the SMP foamincludes a channel that includes a portion of the pusher rod and bywhich the SMP foam is slidably coupled to the pusher rod.

Example 18a includes the apparatus of example 2a comprising anendovascular catheter, wherein the pusher rod, the SMP foam, and the SMmetal are all configured to simultaneously fit within the catheter.

Example 19a includes the apparatus of example 18a, wherein the catheterhas a maximum outer diameter and the second maximum diameter of the SMPfoam in the expanded configuration is at least 150% of the maximum outerdiameter of the catheter.

Example 20a includes the apparatus of example 2a, wherein in theexpanded configuration the second maximum diameter of the SM metal isless than the second maximum diameter of the SMP foam.

Example 21a includes the apparatus of example 2a, wherein in theexpanded configuration the SM metal compresses the SMP foam axially andexpands the SMP foam radially.

Example 22a includes the apparatus of example 21a, wherein the pusherrod includes an additional SM metal.

Example 23a includes the apparatus of example 2a, wherein the SMP foamand the SM metal transition to the expanded configurationnon-simultaneously.

Example 1b includes a system comprising: a pusher rod having proximaland distal ends; a shape memory polymer (SMP) foam slidably coupled tothe pusher rod and adjacent the distal end of the pusher rod; and ashape memory (SM) metal coupled to the pusher rod distal to the SMPfoam; wherein the pusher rod, the SMP foam, and the SM metal are coupledto each other such that: (a)(i) a distal portion of the SM metal isstatically coupled to the pusher rod and a proximal portion of the SMmetal is slideably coupled to the pusher rod; (a)(ii) in a non-expandedconfiguration the SM metal and the SMP foam each have first maximumdiameters orthogonal to the pusher rod; and (a)(iii) in an expandedconfiguration the SM metal and the SMP foam each have second maximumdiameters orthogonal to the pusher rod and greater than the respectivefirst maximum diameters.

A “pusher rod” constitutes a medium for advancing the system. The rodmay constitute a mere wire or guide wire, such as wire 104 of FIG. 1.The rod may be monolithic and extend proximal to foam 108, through foam108, through SM metal 112, and distal to metal 112. However, it may benon-monolithic and be composed of pieces coupled together via welding,epoxies, adhesives and the like. The guide wire may run through SM metal112 or may stop proximal to the SM metal in varying embodiments.

In an embodiment collar 408A (FIG. 4A) is statically coupled to rod 434Awhile collar 404A is dynamically coupled to rod 434A and may movetowards 408A when 412A contracts axially and expands radially (i.e.,when transitioning from non-expanded configuration (e.g., FIG. 4A) toexpanded configuration (e.g., FIG. 4B)). In an embodiment, the pusherrod may couple to a proximal portion of a SM material (e.g., SM metal orSMP) and the distal portion of the SM material may not directly coupledto the pusher rod but may be free to expand and contract to change theradial diameter of the SM material to provide support for a SMP foamthat is proximal or distal to the support member that includes the SMmaterial. A support member such as SM metal 112 may be duplicated and beboth proximal and distal to the SMP foam in some embodiments.

The SM metal expands from a first max diameter 440 to a second maxdiameter 441. The same is true for the SMP foam at diameters 240, 241(FIG. 2A).

In an embodiment the SMP foam is an open cell polyurethane foam. By“slideably coupled” the foam is able to slide along the rod so it is notfixedly or statically coupled but is still coupled that goes beyondmerely resting against the rod. In other embodiments the foam isstatically coupled to the pusher rod. In some embodiments only a portionof the SMP foam is statically coupled to the pusher rod thereby allowinganother portion to dynamically couple to the pusher rod. The dynamicallycoupled portion may have linear expansion and/or radial expansion.

The SM metal may include an alloy of metals and the like. The SM metalmay include nitinol but may include other material combinations in otherembodiments.

Example 2b includes the system of example 1b wherein (b)(i) in thenon-expanded configuration the SM metal and the SMP foam each have firstmaximum lengths parallel to the pusher rod; (b)(ii) in the expandedconfiguration the SM metal and the SMP foam each have second maximumlengths parallel to the pusher rod; and (b)(iii) the first maximumlength of the SM metal is longer than the second maximum length of theSM metal.

For example, SM metal moves from length 442 to length 443. In someembodiments the SMP foam may change in length however in otherembodiments the length of the SMP foam may be generally constant withthe expansion of the foam mainly occurring radially. As used herein, andunless context dictates otherwise, “radial” is meant to be orthogonal toa pusher wire and “axial” is meant to be parallel to the pusher wire(when the pusher wire is linear and non-arcuate).

Example 3b includes the system of example 1b wherein the SM metalcontracts axially when transitioning from the non-expanded state to theexpanded state.

Example 4b includes the system of example 3b wherein (b)(i) in thenon-expanded configuration the proximal portion of the SM metal islocated a first axial distance away from a distal face of the SMP foam;(b)(ii) in the expanded configuration the proximal portion of the SMmetal is located a second axial distance away from the distal face ofthe SMP foam, and (b)(iii) the second axial distance is greater than thefirst axial distance.

For example, in FIG. 7 the first axial distance 741 may constitute thedistance between foam 708 and SM metal 704 in the non-expanded statewhile distance 742 constitutes the distance between foam 708 and SMmetal 704 in the expanded state (with the differential distance shown byelement 743). In some embodiments distance 741 may be 0 mm (i.e., thefoam and SM metal contact each other) and foam 708 may slide alongdistance 743 to contact element 704 when proximal face 750 contacts ablood clot (which provides resistance to proximal movement of the foam)due to withdrawal of rod 718042 in the proximal direction 751.

In an embodiment, foam may expand linearly to cover some or all ofdistance 743 with or without being forced distally by an obstacle suchas a blood clot. In other words, the foam's linear expansion (in someembodiments but not all embodiments) may traverse some or all ofdistance 743. The force between the foam and SM metal may be heightenedwhen the foam's proximal portion encounters resistance (e.g., bloodclot). In an embodiment, due to the linear expansion of the foam (e.g.,in the distal direction) the SM metal may place axial and/or non-axialforce against the foam to help the foam expand and fill the bloodvessel. The force may be heightened when the foam's proximal portionencounters resistance (e.g., blood clot).

Example 5b includes the system of example 4b wherein the SMP foam isconfigured to slide distally and traverse the second axial distance whenthe pusher rod is moved proximally and a proximal face of the SMP foamabuts an obstacle that resists proximal movement of the SMP foam.

Such an “obstacle” may include, for example, a blood clot or otherelement (e.g., another SMP foam previously implanted, another medicaldevice previously implanted).

Example 6b includes the system of example 5b wherein when the pusher rodis moved proximally and a proximal face of the SMP foam abuts anobstacle the proximal portion of the SM metal both compresses the SMPfoam axially parallel to the pusher rod, and expands the SMP foamradially orthogonal to the pusher rod and away from the pusher rod.

An embodiment may include a flower like nitinol support piece that isdesigned to compress the foam axially and expand the foam radially whenretracted. Doing so fills the breadth of the vessel and preventsfragments of the blood clot from traveling past the device.

Another version of Example 6b includes the system of example 5b whereinwhen the pusher rod is moved proximally and the proximal face of the SMPfoam abuts the obstacle the proximal portion of the SM metal suppliesboth axial force against the SMP foam and non-orthogonal non-axial forceagainst the SMP foam.

For example, when foam 312 c contacts strut 316 c a force will be putupon foam 312 c. The force may be directed in direction 352, which hasboth axial components and orthogonal components. Thus, the“non-orthogonal non-axial force” may be projected along vector 352. Thisis important in that it forces foam 312 c against vessel walls (due tothe non-axial component) to help prevent downstream debris (and does soin a gentle manner that does not overly damage foam 312 c). Further, theSM metal may have purely axial forces 351 in addition to the non-axialforce 352. The non-axial force along direction 352 may help expand a SMPfoam that is slow to expand or is otherwise having difficulty expandingdue to any number of reasons (e.g., insufficient actuator stimulus,relatively weak expansion force inherent to the foam).

Example 7b includes the system of example 3b, wherein the SM metalcomprises at least two struts that couple the distal portion of the SMmetal to the proximal portion of the SM metal.

Example 8b includes the system of example 7b comprising a conduitcoupled to proximal portions of the at least two struts, wherein theconduit is slideably coupled to the pusher rod.

For example, collar 404 a constitutes such a conduit. A conduit need notbe a pipe but may instead be a mere channel for conveying a substratesuch as rod 434 a.

Example 9b includes the system of example 8b wherein the conduit slidesdistally along the pusher rod when the SM metal transitions from thenon-expanded configuration to the expanded configuration.

Example 10b includes the system of example 8b, wherein the conduit andthe at least two struts are all monolithic with each other.

For example, see element 808 of FIG. 8.

Example 11b includes the system of example 8b comprising an additionalconduit coupled to distal portions of the at least two struts.

For example, see element 408A of FIG. 4A.

Example 12b includes the system of example 7b wherein the at least twostruts directly contact a distal face of the SMP foam when the pusherrod is moved proximally and a proximal face of the SMP foam abuts anobstacle that resists proximal movement of the SMP foam.

See, for example, FIG. 3C.

Example 13b includes the system of example 12b wherein the at least twostruts are substantially linear in the non-expanded configuration andsubstantially arcuate in the expanded configuration.

Example 14b includes the system of example 12b wherein the at least twostruts do not contact the distal face of the SMP foam in thenon-expanded configuration.

Example 15b includes the system of example 3b wherein the pusher rodpasses through the SMP foam and at least a portion of the SM metal whenthe SMP foam and the SM metal are each in the non-expandedconfiguration.

For example, see element 104 of FIG. 1.

Example 16b includes the system of example 15b, wherein a first portionof the pusher rod is proximal to the SMP foam, a second portion of thepusher rod passes through the SMP foam when the SMP foam is in thenon-expanded configuration, and a third portion of the pusher rod passesthrough the portion of the SM metal when the SM metal is in thenon-expanded configuration.

For example, see element 104 of FIG. 1.

Example 17b includes the system of example 16b, wherein the first,second, and third portions of the pusher rod are monolithic with eachother.

For example, see element 808 of FIG. 8.

Example 18b includes the system of example 3b, wherein the SMP foamtransitions from the unexpanded configuration to the expandedconfiguration in response to thermal stimulus.

Such a thermal stimulus may be due to body temperature, bodily fluids,blood, optical energy, resistive heating, a solution (e.g., saline)administered to the device, and the like. The stimulus may take place inconjunction with other actions such as plasticization and the like.

Example 19b includes the system of example 3b, wherein the SMP foamincludes a channel that includes a portion of the pusher rod and bywhich the SMP foam is slidably coupled to the pusher rod.

Example 20b includes the system of example 3b comprising a sheath,wherein the pusher rod, the SMP foam, and the SM metal are allconfigured to simultaneously fit within the sheath.

Example 21b includes the system of example 20b, wherein the sheath has amaximum outer diameter and the second maximum diameter of the SMP foamin the expanded configuration is at least 150% of the maximum outerdiameter of the sheath.

Other embodiments are not so limited and may include 110% , 130%, 170%,190% or more.

Example 22b includes the system of example 3b, wherein in the expandedconfiguration the second maximum diameter of the SM metal is less thanthe second maximum diameter of the SMP foam.

Such a situation may be desirable in some embodiments where the SM metalis not meant to expand to a point where it contacts vessel walls butwhere the SMP foam should necessarily contact the vessel walls.

Example 23b includes the system of example 3b, wherein the pusher rodincludes an additional SM metal.

Example 24b includes the system of example 3b, wherein the SMP foam andthe SM metal transition to the expanded configurationnon-simultaneously.

For example, the SM metal may transition as soon as it is deployed fromthe sheath (sometimes referred to as a catheter) while the foam maydeploy from the sheath but not transition until it is warmed by blood,saline, resistive heating, and the like.

Example 25b includes a system comprising: a sheath and a pusher rod; ashape memory polymer (SMP) foam slidably coupled to the pusher rod; anda shape memory (SM) metal coupled to the pusher rod distal to the SMPfoam; wherein the pusher rod, the SMP foam, and the SM metal are coupledto each other such that: (a) in a first state the pusher rod, the SMPfoam, and the SM metal are included in the sheath; (b) in a second statethe pusher rod, the SMP foam, and the SM metal are deployed from thesheath and, in response to being deployed from the sheath, the SM metalcontracts axially, expands radially, and a proximal-most edge of the SMmetal moves away from the SMP foam, (c) in a third state the SMP foamexpands radially in response to being deployed from the sheath, and (d)in a fourth state the radially expanded SMP foam slides distally alongthe pusher rod until a distal face of the SMP foam contacts the radiallyexpanded SM metal.

For instance, in the third state the SMP foam expands radially inresponse to being deployed from the sheath and may expand in response toother actions as well (e.g., exposure to thermal stimulus).

Example 26b includes the system of example 25b, wherein in the fourthstate the SM metal compresses the SMP foam axially and expands the SMPfoam radially.

Another version of example 26b includes the system of example 25b,wherein in the fourth state the SM metal supplies both axial forceagainst the SMP foam and non-orthogonal, non-axial force against the SMPfoam.

Example 27b includes the system of example 26b, wherein: the SM metalcomprises a conduit and at least two struts; the conduit is coupled toproximal portions of the at least two struts; and the conduit isslideably coupled to the pusher rod.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. This description and the claims following include terms, suchas left, right, top, bottom, over, under, upper, lower, first, second,etc. that are used for descriptive purposes only and are not to beconstrued as limiting. The embodiments of a device or article describedherein can be manufactured, used, or shipped in a number of positionsand orientations (thereby affecting “distal” vs “proximal” and the like.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in light of the aboveteaching. Persons skilled in the art will recognize various equivalentcombinations and substitutions for various components shown in theFigures. It is therefore intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

What is claimed is:
 1. A system comprising: a pusher rod having proximaland distal ends; a shape memory polymer (SMP) foam slidably coupled tothe pusher rod and adjacent the distal end of the pusher rod; and ashape memory (SM) metal coupled to the pusher rod distal to the SMPfoam; wherein the pusher rod, the SMP foam, and the SM metal are coupledto each other such that: (a)(i) a distal portion of the SM metal isstatically coupled to the pusher rod and a proximal portion of the SMmetal is slideably coupled to the pusher rod; (a)(ii) in a non-expandedconfiguration the SM metal and the SMP foam each have first maximumdiameters orthogonal to the pusher rod; and (a)(iii) in an expandedconfiguration the SM metal and the SMP foam each have second maximumdiameters orthogonal to the pusher rod and greater than the respectivefirst maximum diameters.